Looking for T-shirt, DTG, software/app/plugin/anything that works well with Squarespace.

Site URL: https://certifiedprintco.com/

I am looking for t-shirt design software that can integrate with Squarespace's eCommerce platform. Ideally, it would be DTG (direct to garment) software that has a 3d model GUI on the front end that would feed ready to print files to the back end. If it doesn't directly integrate with Squarespace, at least software/web application that can be integrated into the site via code which means it would also be it's own ecommerce platform or api to one. So far I have only found t-shit and DTG software api's for shopify and woo.

Check out this design